The purpose of this study to develop statistical and informatics tools for analyzing and visualizing actigraphy data linked to fatigue in sleep medicine center patients. An actigraph is a watch-like device attached to the wrist that uses an accelerometer to measure movement nearly continuously over several days. An American Academy of Sleep Medicine 2002 report defines the practice parameters for the use of actigraphy as a useful tool for detecting sleep in healthy individuals, assessing specific aspects in insomnia and restless leg syndrome, and a useful adjunct to a detailed history and subjective sleep diary for diagnosing and treating insomnia, circadian-rhythm disorders, and excessive sleepiness. Concurrent with these recommendations is an increased interest in the use of actigraphy as a tool for objectively measuring fatigue. With improved high-end statistical methods for analyzing this data, actigraphy has the potential to become more important as an objective diagnostic tool for determining fatigue, sleep abnormalities and assessing response to treatment. Other special areas of neurology and medicine where actigraphy can be used more effectively include restless leg syndrome, the elderly and nursing home patients with and without dementia, newborns, infants, children, and adolescents, hypertensive individuals, depressed or schizophrenic patients, and individuals in inaccessible situations. PUBLIC HEALTH RELEVANCE: With improved high-end statistical methods for analyzing actigraphy data, actigraphy has the potential to become more important in clinical medicine and research as an objective diagnostic tool for determining fatigue, sleep abnormalities and assessing response to treatment. Other special areas of neurology and medicine where actigraphy can be used more effectively include restless leg syndrome, the elderly and nursing home patients with and without dementia, newborns, infants, children, and adolescents, hypertensive individuals, depressed or schizophrenic patients, and individuals in inaccessible situations.